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.TH LROUND 3  2021-03-22 "" "Linux Programmer's Manual"
.SH NAME
lround, lroundf, lroundl, llround, llroundf, llroundl \- round to
nearest integer
.SH SYNOPSIS
.nf
.B #include <math.h>
.PP
.BI "long lround(double " x );
.BI "long lroundf(float " x );
.BI "long lroundl(long double " x );
.PP
.BI "long long llround(double " x );
.BI "long long llroundf(float " x );
.BI "long long llroundl(long double " x );
.fi
.PP
Link with \fI\-lm\fP.
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
All functions shown above:
.nf
    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
.fi
.SH DESCRIPTION
These functions round their argument to the nearest integer value,
rounding halfway cases away from zero,
regardless of the current rounding direction (see
.BR fenv (3)).
.PP
Note that unlike the
.BR round (3)
and
.BR ceil (3),
functions, the return type of these functions differs from
that of their arguments.
.SH RETURN VALUE
These functions return the rounded integer value.
.PP
If
.I x
is a NaN or an infinity,
or the rounded value is too large to be stored in a
.I long
.RI ( "long long"
in the case of the
.B ll*
functions),
then a domain error occurs, and the return value is unspecified.
.\" The return value is -(LONG_MAX - 1) or -(LLONG_MAX -1)
.SH ERRORS
See
.BR math_error (7)
for information on how to determine whether an error has occurred
when calling these functions.
.PP
The following errors can occur:
.TP
Domain error: \fIx\fP is a NaN or infinite, or the rounded value is too large
.\" .I errno
.\" is set to
.\" .BR EDOM .
An invalid floating-point exception
.RB ( FE_INVALID )
is raised.
.PP
These functions do not set
.IR errno .
.\" FIXME . Is it intentional that these functions do not set errno?
.\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6797
.SH VERSIONS
These functions first appeared in glibc in version 2.1.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR lround (),
.BR lroundf (),
.BR lroundl (),
.BR llround (),
.BR llroundf (),
.BR llroundl ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.
.SH SEE ALSO
.BR ceil (3),
.BR floor (3),
.BR lrint (3),
.BR nearbyint (3),
.BR rint (3),
.BR round (3)
.SH COLOPHON
This page is part of release 5.13 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%https://www.kernel.org/doc/man\-pages/.
